Technical Field
The present invention relates to a rotor blade of a wind turbine. The present invention moreover relates to a wind turbine.
Description of the Related Art
Wind turbines are a matter of common knowledge. The most common wind turbines nowadays are the so-called horizontal axis wind turbines, which are also the subject of the present application. Modern wind turbines are adapted to the wind conditions expected at their installation site. One can differentiate, in particular, between wind turbines for strong wind sites and wind turbines for weak wind sites. Further subcategorization is possible, if necessary.
As compared to wind turbines for sites with higher average wind speeds, wind turbines for weak wind sites feature longer rotor blades that are more delicate, at least section-wise. This way, such longer rotor blades can over-sweep a larger disk area and extract as much energy from the wind as possible, even in weak wind conditions. Heavy loads caused by strong wind are comparatively rare.
When building such rotor blades, one must make sure to design especially their central area narrow enough to make them as light as possible but provide them, at the same time, with sufficient load capacity for the blade. Especially in the area of the rotor blade that is central in relation to the radial direction of the rotor, it can be difficult to accommodate the described requirements on stability and load capacity of the rotor blade to the required aerodynamic design.
Sometimes, the scope for designing the aerodynamic profile may be so little that, although one will achieve an aerodynamic profile with good properties, slight deviations of this ideal aerodynamic profile may have a significant effect on the flow properties. Especially contamination of the rotor blade may cause an unwanted early stall that would not, or at least not to that extent, happen with a non-contaminated blade. Sometimes, even raindrops can cause a significant contamination of the blade.